820-4924 freezes on loading

[daniel_andrei1996]

820-4924 with unknown history
Some general nastiness, signs of liquid around the LCD connector but overall nothing terrible
Powers on fine but when booting macOS will freeze with the loading bar around 75%. Sometimes (rarely) it will boot fully in which case it seems to work fine.
Have tried cleaning in ultrasonic, no luck
Tried clean ME bios, no luck
Completes hardware diagnostic with no issues found
Ran memtest with no issues found

I would really appreciate any suggestions at this point

 

[2informaticos]

PRAM reset as first step.
Also try known good working FULL BIOS; clean ME of course.

Disconnect internal SSD and try your USB test OSX.
Did you clean ME with Medusa?

 

[daniel_andrei1996]

the bios I tried is the clean ME bios you posted in another forum https://boards.rossmanngroup.com/for...f-at-40-econds I don't have Medusa yet.
tried pram reset with no luck, it does the reset but freezes the same
If I try to reinstall MacOS Catalina it goes through most of the process but eventually gets stuck again
Removed SSD and connected usb drive with High Sierra, same behaviour.
can boot from ubuntu liveusb with no issue
If I boot into windows it mostly works but freezes if I try to load Hwinfo or install bootcamp drivers

EDIT: Also forgot to say but if I try to boot with 85W magsafe and no battery the laptop freezes when loading and eventually reboots, but this seems normal for the 4924 from what I see. Just thought I'd mention it

 

[daniel_andrei1996]

so, adding to the weirdness:

I've experimented a bit more and it seems I can reliably boot OSX on the macbook if an external display is attached via HDMI or DP, even if still using the retina as main display
Once fully booted into the OS I can disconnect the extra screen and the laptop will continue to work normally. I can even run stress tests or geekbench with no issue. Also all the sensor values read normal
After starting with an external display the mac seems to fully load every time and work as normal, just with the built-in display, even shut down and reboot normally.
The issue only returns if unplugging the battery and charger for a while, in which case I have to use an external screen again or the laptop freezes

Truly bizarre issue that I can't find an explanation for

 

[2informaticos]

I didn't see 4924 to freeze without battery.
Be sure to use Magsafe 2 charger; not 1 -> 2 adapter.

Catalina installation, as HS and Mojave, affects the BIOS.
And people reported problems, from time to time.
So, after flashing clean ME BIOS, test the machine with external OSX (preinstalled).

 

[daniel_andrei1996]

ok so I flashed the clean bios again via programmer
Tried to boot High Sierra from USB drive, with no battery connected.
Tried with original 85W magsafe 2 lead on my PSU, loading bar gets to 60-70% and the screen goes black and I hear the "dong" startup sound, then the os starts loading again.
Interestingly I also tried with genuine magsafe 2 65W charger, which gets orange light but the laptop won't boot at all, unless I start in SMC bypass mode in which case it freezes again but doesn't reboot.

 

[2informaticos]

Looks like you have problems with some SMC sensor.
You should reball SMC and inspect all resistor around it.
Check correct resistance between pins 17/18 and 27/28 of U7100.

Inspect all power sensors, pages 42-44...

 

[daniel_andrei1996]

Apologies for the confusion, turns out my 65W magsafe was failing. Sadly I only realised that after reballing SMC. Got a new one and the laptop powers fine on it without battery
Luckily, I also found R2042 had a hole in it and was reading 500k, replaced it with 0ohm from donor. I think this was causing clock instability and my freezing, as the problem seems to be gone now
One last thing, since I'm still using the clean ME bios linked above, could you use medusa and change the serial number to c02qnn4sfvh3 so it matches the bottom cover?
Thanks a lot for everything

 

[2informaticos]

Original BIOS should work, as you've find the culprit now.
If not, let me know and I'll try to do it later.
Bafta!

 

[daniel_andrei1996]

tried the original bios again and it seems to load slow. It does it eventually but it takes a while so might still be some issue there.
If you can change the serial in the clean bios that would be fantastic.
Thanks again

 

[2informaticos]

Copy/paste from the same thread you've got the BIOS:
"Copy entire Fsys block from your original BIOS to the new BIOS file (the updated one)."

You don't need to fix checksum after that.